Class StringConcatenation

java.lang.Object

edu.umd.cs.findbugs.visitclass.BetterVisitor

edu.umd.cs.findbugs.visitclass.PreorderVisitor

edu.umd.cs.findbugs.visitclass.AnnotationVisitor

edu.umd.cs.findbugs.visitclass.DismantleBytecode

edu.umd.cs.findbugs.BytecodeScanningDetector

edu.umd.cs.findbugs.bcel.OpcodeStackDetector

edu.umd.cs.findbugs.detect.StringConcatenation

All Implemented Interfaces:

Detector, Priorities, StatelessDetector, Cloneable, org.apache.bcel.classfile.Visitor

public class StringConcatenation
extends OpcodeStackDetector
implements StatelessDetector

Find occurrences of using the String "+" or "+=" operators within a loop. This is much less efficient than creating a dedicated StringBuffer object outside the loop, and then appending to it.

Nested Class Summary

Nested classes/interfaces inherited from class OpcodeStackDetector

OpcodeStackDetector.WithCustomJumpInfo

Field Summary

Fields

Modifier and Type	Field	Description
private final BugReporter	bugReporter
private Map<Integer,Integer>	clobberedRegisters
(package private) static final int	CONSTRUCTED_STRING_ON_STACK
private int	createPC
private static final boolean	DEBUG
(package private) static final int	POSSIBLE_CASE
private boolean	reportedThisMethod
(package private) static final int	SEEN_APPEND1
(package private) static final int	SEEN_APPEND2
(package private) static final int	SEEN_NEW
(package private) static final int	SEEN_NOTHING
private int	state
private int	stringSource

Fields inherited from class OpcodeStackDetector

stack

Fields inherited from class DismantleBytecode

codeBytes, lineNumberTable, M_BR, M_CP, M_INT, M_PAD, M_R, M_UINT

Fields inherited from interface Priorities

EXP_PRIORITY, HIGH_PRIORITY, IGNORE_PRIORITY, LOW_PRIORITY, NORMAL_PRIORITY

Constructor Summary

Constructors

Constructor	Description
StringConcatenation(BugReporter bugReporter)

Method Summary

Modifier and Type	Method	Description
private int	getRegisterOnStack()
private int	getRegisterOnStack(int idx)
private void	reset()
void	sawOpcode(int seen)	By default, this method will not be called when stack is TOP.
private boolean	storeIntoRegister(int seen, int reg)
void	visit(org.apache.bcel.classfile.Method obj)

Methods inherited from class OpcodeStackDetector

afterOpcode, beforeOpcode, getStack, isUsingCustomUserValue, visitCode

Methods inherited from class BytecodeScanningDetector

getClassContext, report, shouldVisitCode, visitClassContext

Methods inherited from class DismantleBytecode

areOppositeBranches, atCatchBlock, getBranchFallThrough, getBranchOffset, getBranchTarget, getClassConstantOperand, getClassDescriptorOperand, getCodeByte, getConstantRefOperand, getDefaultSwitchOffset, getDottedClassConstantOperand, getFieldDescriptorOperand, getIntConstant, getLongConstant, getMaxPC, getMethodDescriptorOperand, getNameConstantOperand, getNextCodeByte, getNextOpcode, getNextPC, getOpcode, getPC, getPrevOpcode, getRefConstantOperand, getRefFieldIsStatic, getRegisterOperand, getSigConstantOperand, getStringConstantOperand, getSwitchLabels, getSwitchOffsets, getXClassOperand, getXFieldOperand, getXMethodOperand, isBranch, isMethodCall, isRegisterLoad, isRegisterStore, isRegisterStore, isReturn, isShift, isSwitch, isWideOpcode, printOpCode, sawBranchTo, sawClass, sawDouble, sawField, sawFloat, sawIMethod, sawInt, sawLong, sawMethod, sawRegister, sawString, visit

Methods inherited from class AnnotationVisitor

getAnnotationParameterAsEnum, getAnnotationParameterAsString, getAnnotationParameterAsStringArray, visitAnnotation, visitAnnotation, visitParameterAnnotation, visitParameterAnnotation, visitSyntheticParameterAnnotation

Methods inherited from class PreorderVisitor

amVisitingMainMethod, asUnsignedByte, doVisitMethod, getClassDescriptor, getClassName, getCode, getConstantPool, getDottedClassName, getDottedFieldSig, getDottedMethodSig, getDottedSuperclassName, getField, getFieldDescriptor, getFieldIsStatic, getFieldName, getFieldSig, getFullyQualifiedFieldName, getFullyQualifiedMethodName, getMethod, getMethodDescriptor, getMethodName, getMethodSig, getMethodVisitOrder, getNumberArguments, getNumberMethodArguments, getPackageName, getSizeOfSurroundingTryBlock, getSizeOfSurroundingTryBlock, getSourceFile, getStringFromIndex, getSuperclassName, getSurroundingCaughtExceptions, getSurroundingCaughtExceptions, getSurroundingCaughtExceptionTypes, getSurroundingTryBlock, getSurroundingTryBlock, getThisClass, getXClass, getXField, getXMethod, hasInterestingClass, hasInterestingMethod, isVisitMethodsInCallOrder, setupVisitorForClass, setVisitMethodsInCallOrder, shouldVisit, toString, visitAfter, visitAfter, visitAnnotationDefault, visitAnnotationEntry, visitBootstrapMethods, visitConstantInvokeDynamic, visitConstantMethodHandle, visitConstantMethodType, visitConstantModule, visitConstantPackage, visitConstantPool, visitEnclosingMethod, visitingField, visitingMethod, visitInnerClasses, visitJavaClass, visitLineNumberTable, visitLocalVariableTable, visitMethodParameters, visitParameterAnnotationEntry, visitStackMap, visitStackMapEntry

Methods inherited from class BetterVisitor

clone, report, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visitCodeException, visitConstantClass, visitConstantDouble, visitConstantFieldref, visitConstantFloat, visitConstantInteger, visitConstantInterfaceMethodref, visitConstantLong, visitConstantMethodref, visitConstantNameAndType, visitConstantString, visitConstantUtf8, visitConstantValue, visitDeprecated, visitExceptionTable, visitField, visitInnerClass, visitLineNumber, visitLocalVariable, visitLocalVariableTypeTable, visitMethod, visitSignature, visitSourceFile, visitSynthetic, visitUnknown

Methods inherited from class Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface StatelessDetector

clone

Methods inherited from interface org.apache.bcel.classfile.Visitor

visitConstantDynamic, visitMethodParameter, visitModule, visitModuleExports, visitModuleMainClass, visitModuleOpens, visitModulePackages, visitModuleProvides, visitModuleRequires, visitNestHost, visitNestMembers, visitRecord, visitRecordComponent, visitStackMapType

Field Details

DEBUG

private static final boolean DEBUG

SEEN_NOTHING

static final int SEEN_NOTHING

See Also:

• Constant Field Values

SEEN_NEW

static final int SEEN_NEW

See Also:

• Constant Field Values

SEEN_APPEND1

static final int SEEN_APPEND1

See Also:

• Constant Field Values

SEEN_APPEND2

static final int SEEN_APPEND2

See Also:

• Constant Field Values

CONSTRUCTED_STRING_ON_STACK

static final int CONSTRUCTED_STRING_ON_STACK

See Also:

• Constant Field Values

POSSIBLE_CASE

static final int POSSIBLE_CASE

See Also:

• Constant Field Values

bugReporter

private final BugReporter bugReporter

reportedThisMethod

private boolean reportedThisMethod

stringSource

private int stringSource

createPC

private int createPC

state

private int state

clobberedRegisters

private Map<Integer,Integer> clobberedRegisters

Constructor Details

StringConcatenation

public StringConcatenation(BugReporter bugReporter)

Method Details

visit

public void visit(org.apache.bcel.classfile.Method obj)

Overrides:

visit in class BetterVisitor

reset

private void reset()

storeIntoRegister

private boolean storeIntoRegister(int seen,
 int reg)

getRegisterOnStack

private int getRegisterOnStack()

getRegisterOnStack

private int getRegisterOnStack(int idx)

sawOpcode

public void sawOpcode(int seen)

Description copied from class: OpcodeStackDetector

By default, this method will not be called when stack is TOP. To change this behavior, override #beforeOpcode(int) and change to return true even if stack is TOP.

see Using FindBugs for Research to learn lattice and what TOP means.

Specified by:

sawOpcode in class OpcodeStackDetector

See Also:

• OpcodeStackDetector.beforeOpcode(int)